Question

A certain buffer solution contains equal concentration of $X^{⊝}$ and HX. The $K_b$ for $X^{⊝}$ is ${10}^{-10}$. The pH of the buffer is:

• A. 4
• B. 7
• C. 10
• D. 14

Answer 1

The correct option is A 4

We know,

$K_a=\frac{K_w}{K_b}=\frac{{10}^{-14}}{{10}^{-10}}={10}^{-4}$

and

$pH=p{K}_a+log\frac{\left[salt\right]}{\left[acid\right]}⟹pH=4$ as concentration of salt and acid is equal, $\frac{\left[salt\right]}{\left[acid\right]}=1$